In his talk “Drinking in the Data: Fluid Intake and Health,” Rosner disproved several urban myths by explaining that some common hydration guidelines come with little to no scientific backing. For example, many have heard they should drink eight 8-oz. glasses of water a day, but Rosner said the “eight-by-eight prescription” has no scientific basis whatsoever.

Rosner also dismissed the lay-literature claim that people need to drink ahead of thirst.

“It’s really, I think, hard to imagine that evolutionary development somehow left us with a chronic water deficit that has to be compensated by artificially forcing fluid intake. It makes no sense,” Rosner said.

Rosner concluded there is “scant evidence” to support hydration guidelines that state arbitrary and high fluid intake improves health. While some very specific medical conditions might be alleviated by increased fluid intake, Rosner said it’s very concerning that members of the general public mistakenly believe the thirst sensation cannot adequately prevent dehydration.

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